What's on your bench today?

[spudulike]

what are your thoughts of a oleo-mac 942 please be gentle with me

 

i,ve been asked to repair this for a builder/roofer i hav,nt called him yet etc he just said it stopped and i hate liars i,ve flicked the exhaust off and grimdeath has had a visit no oil in petrol etc

 

i hate it when a saw has been run on raw petrol makes my blood boil what should i do repair it or lob it in the bin as i know nowt about these saws are they chepo,s etc as it reminds me of a husky to be honest >>>>> is it worth a piston kit or a pot n piston kit ????? as i,am unsure if its chrome bore etc both are badly marked up it must of been hot and running at full chat when it failed etc

 

Sorry, Not familiar with this saw, it is worth fixing if the saw will be worth more either in sentimental value or £££ value after the work has been done.

[spudulike]

IMO replacing a piston after a serious siezer is so risky, just one speck of metal from the old piston and your back to square one. Ive got the Tshirt!!

 

Done many now and personally always prefer to salvage an OEM cylinder and use a quality grade piston than using aftermarket P&Cs.

 

I am a bit meticulous in what I do and how I do it - there will be no transfer left when I have cleaned a bore of transfer aluminium but you are right that the bore needs to be 100% clear of residual aluminium otherwise you will do another ring and piston.

[swinny]

Just curious, i have a 2005 200t and its a good runner, just wondering with the age etc if it would be worth doing a compression test on it and maybe fitting a fresh piston to it, seem's as though they've stopped selling the 200t?

 

Just a thought

[Chris Sheppard]

Getting a bit of a backlog here at the mo but making some progress on the old Husky 181 as managed to pick up an unused genuine barrel and piston kit for it for £30 Really should get round to taking the rest of it to bits

 

Got a real tidy 42 special that wants a bit of fettling (don't think it's owt too major), and then the good running 42 (1989 Vintage!) decided to spit it's dummy out just before christmas as well and got shoved in the naughty corner with the other.

 

Out of interest, does anyone know what actual differences there are between a plain old 42 and a 242?

[spudulike]

Just curious, i have a 2005 200t and its a good runner, just wondering with the age etc if it would be worth doing a compression test on it and maybe fitting a fresh piston to it, seem's as though they've stopped selling the 200t?

 

Just a thought

 

Always worth doing, only seen one bore that had worked through the plate in to the aluminium and that was down to ingress of crap through the air filter.

 

If it has 145psi+ all is good, you can take it down and see how good the bore to piston clearance is and the condition of the parts but it will put a bit of punch back in a tired saw. Just need to endsure the crankshaft bearings are good and the carb etc are all servicable.

[[email protected]]

pt new ignition pack/lead on 55 today and shes a goeeerrrr!!!!!!!

[NI Tree]

Getting a bit of a backlog here at the mo but making some progress on the old Husky 181 as managed to pick up an unused genuine barrel and piston kit for it for £30 Really should get round to taking the rest of it to bits

 

Got a real tidy 42 special that wants a bit of fettling (don't think it's owt too major), and then the good running 42 (1989 Vintage!) decided to spit it's dummy out just before christmas as well and got shoved in the naughty corner with the other.

 

Out of interest, does anyone know what actual differences there are between a plain old 42 and a 242?

 

i think one is a closed port and the other open

[blazer]

i think one is a closed port and the other open

 

Could you please explain the difference between open & closed port:confused1:

Thanks in advance - done a fair bit with engines but not too hot on some tech aspects.

[spudulike]

Could you please explain the difference between open & closed port:confused1:

Thanks in advance - done a fair bit with engines but not too hot on some tech aspects.

 

Right - by open port, we are talking transfer ports, the ones that move fuel vapour from the crank case to the combustion chamber.

 

An open port will look like an open channel up both sides of the cylinder 90 degs from the inlet and exhaust ports.

 

A closed transfer port will have a hole or holes near the base of the cylinder and a hole or holes further up the cylinder and the channel will be covered by the inner wall of the cylinder.

 

Very generally, closed port is found on pro saws and open on semi pro or homeowner. There are exceptions - the MS200 has open ports.

 

A closed port will lower the amount of play between the bore and piston and give longer life....allegedly!

 

Pistons can also have closed or open ports/sides. The open ports/sides allow for more fuel vapour to be transfered and would say it makes the saw more powerful but the 346 and 357 have closed sides!!

 

You will be able to see some examples if you scroll through this thread - most of the pics will have closed ports.

[blazer]

Many thanks Spud, from memory most of the old 2T bikes I worked on were open ported, I just remember the gaskets with holes for the side of the transfer ports but the good ones didn't breakdown so I didn't find out how designs had changed, also by luck I haven't needed to take the top any of my saws.

 

I assume a closed port engine could have a higher primary compression ratio?

 

I remember a Bultaco bike I had with a split window on the large exhast port, but this used to make a wear mark in the L section top ring loosing some compression.